I wish the world would use ipv6 enough for this to be worth doing, but it's not going to have much benefit to you as there's almost no one using it for smtp, from the last time I checked which was a few months ago, google uses it perfectly, verizon too (maybe a few more cable domains), yahoo looked like they were trying lol, website and some services were v6 this year but smtp was not when I checked, hotmail doesn't use it anywhere from what i can see, aol never will and almost no self hosted mail server will have it. My guess is (unless gmail is where most mail goes) that you might see a few percent like 1-5% of mail ever use it. Not a bad research project or knowing v6, or if you have other reasons, but actual sending out is just not happening any time soon.
I suggest finding a better work around than v6, such as changing the smtp port (I don't know how to do this in postfix but I believe it has this option), or using a different smtp relay (your own hosted somewhere else, 3rd party, etc), or even switching your email on your domain to a service like gmail. Making the default v6 will probably also cause lots of incoming mail problems and as Wietse said you will lose a lot of your internal config. Between the confusion of outside mail servers and your own, you will find lots of confusing issues, there's a reason your ISP doesn't seem to care about blocking the v6 smtp port. Paul On Sat, Mar 25, 2017 at 12:29 PM, Franck MAHE <m...@civis.net> wrote: > Hi Wietse, > > That is to say it must work with a second instance of POSTFIX? > > Let say that it will use IPV6 as default for outgoing smtp and a > fallback on > the same host that will use IPV4. Correct? > > > > Franck MAHE > ------------------------------------------- > > -----Message d'origine----- > De : owner-postfix-us...@postfix.org > [mailto:owner-postfix-us...@postfix.org] De la part de Wietse Venema > Envoyé : samedi 25 mars 2017 15:44 > À : Postfix users <postfix-users@postfix.org> > Objet : Re: Fallback to IPV4 in case of IPV6 is not available > > Postfix can be configured to try IPv6 before IPv4 (with > smtp_address_preference), but that feature is independent from > routing features such as transport_maps, smtp_fallback_relay, and > so on. That is, there are no ipv6_transport_maps or > ipv4_smtp_fallback_relay features. > > I suggest you just keep sending mail via the IPv4 smarthost. > > Wietse >
